Alpha-substituted heteroarylalkyl phosphonate derivatives

ABSTRACT

The present invention relates to novel α-substituted heteroarylalkylphosphonate derivatives and their uses for lowering plasma levels of apo (a), Lp(a), apo B, apo B associated lipoproteins (low density lipoproteins and very low density lipoproteins) and for lowering plasma levels of total cholesterol.

FIELD OF THE INVENTION

This invention relates to substituted heteroarylalkylphosphonatecompositions and therapeutic uses thereof. More specifically, thepresent invention relates to novel α-substitutedheteroarylalkylphosphonate derivatives, processes for their preparation,pharmaceutical compositions containing them and their use in therapy forlowering plasma levels of apo (a) and apo (a) associated lipoprotein(lipoprotein(a) or “Lp(a)”), for lowering plasma levels of apo B and apoB associated lipoproteins (low density lipoproteins and very low densitylipoproteins), and for lowering plasma levels of total cholesterol.

BACKGROUND OF THE INVENTION

Lp(a) is a LDL-like lipoprotein wherein the major lipoprotein, apoB-100, is covalently linked to an unusual glycoprotein, apoprotein(a).The covalent association between apo(a) and apo B to form Lp(a) is asecondary event which is independent of the plasma concentration of apoB. Due to its structural similarity to plasminogen, apo(a) interfereswith the normal physiological thrombosis-hemostasis process bypreventing thrombolysis, that is clot dissolution (see e.g., Biemond BJ, Circulation 1997, 96(5) 1612-1615). The structural feature of Lp(a),where the LDL lipoprotein is linked to apo(a), is thought to beresponsible for its atherogenic and thrombogenic activities.

Elevated levels of Lp(a) have been associated with the development ofatherosclerosis, coronary heart disease, myocardial infarction, cerebralinfarction, restenosis following balloon angioplasty and stroke. Arecent epidemiologic study has provided the clinical proof of a positivecorrelation between plasma Lp(a) concentrations and the incidence ofheart disease (A. G. Bostorn, et al., Journal of American MedicalAssociation 1996, 276, p. 544-548).

Patients that have Lp(a) levels in excess of 20-30 mg/dl run asignificantly increased risk of heart attacks and stroke. An effectivetherapy for lowering Lp(a) does not exist at present because cholesterollowering agents such as the HMGCoA reductase inhibitors do not lowerLp(a) plasma concentrations. The only compound that lowers Lp(a) isniacin, but the high doses necessary for activity are accompanied withunacceptable side-effects. There is, therefore, an unmet therapeuticneed for agents that effectively reduce elevated levels of Lp(a).

International applications WO 97/20307, WO 98/28310, WO 98/28311 and WO98/28312 (Symphar, SmithKline Beecham) describe a series of α-aminophosphonates which have Lp(a) lowering activity. There however remainsthe need to identify further compounds having Lp(a) lowering activity.

SUMMARY OF THE INVENTION

The present invention provides, in a first aspect, a compound of formula(Ia):

or a compound of formula (Ib):

-   in which X¹, X², X³, X⁴ and X⁵ are independently hydrogen, hydroxy,    hydroxymethyl, C₁-C₃ alkoxymethyl, straight or branched C₁-C₈ alkyl,    straight or branched C₁-C₈ alkoxy, C₃-C₆ cycloalkyl, C₃-C₆    cycloalkoxy, cyano, nitro or halogen, wherein said halogen is    fluoro, chloro, bromo or iodo; or X² may be combined with X³, or X⁴    may be combined with X⁵, to form a 5- to 6-membered alkylidenedioxy    ring optionally substituted with a C₁-C₄ alkyl group; X⁴ may be    combined with X⁵ to form a 5- to 6-membered alkylidene ring    optionally substituted with a C₁-C₄ alkyl group;-   R¹ and R² are independently hydrogen or a straight or branched C₁-C₆    alkyl;-   B is CH₂, CH₂—CH₂, CH═CH;-   n is zero or 1;-   m is zero, 1 or 2;-   Het is an optionally substituted heteroaryl group comprising at    least one nitrogen atom, or a pharmaceutically acceptable salt    thereof.

The compound of formula (Ib) may be the Z-isomer, formula (Ib^(Z)):

or the E-isomer, formula (Ib^(E)):

or a mixture thereof.

Compounds of the present invention include:

-   (E)-diethyl    β-(3-ethoxy-4-hydroxyphenyl)-α-(3-pyridyl)vinylphosphonate;-   diethyl β-(3-ethoxy-4-hydroxyphenyl)-α-(3-pyridyl)ethylphosphonate;-   (E)-diethyl    β-(4-hydroxy-2,3,5-trimethylphenyl)-α-(3-pyridyl)vinylphosphonate;-   diethyl    β-(4-hydroxy-2,3,5-trimethylphenyl)-α-(3-pyridyl)ethylphosphonate;-   (E)-diethyl    β-(3,5-dimethoxy-4-hydroxyphenyl)-α-(3-pyridyl)vinylphosphonate;-   diethyl    β-(3,5-dimethoxy-4-hydroxyphenyl)-α-(3-pyridyl)ethylphosphonate;-   (E)-diethyl    β-(3,5-dimethoxy-4-hydroxyphenyl)-α-(5-(2-methylpyridyl))vinylphosphonate;-   diethyl    β-(3,5-dimethoxy-4-hydroxyphenyl)-α-(5-(2-methylpyridyl))ethylphosphonate;-   diisopropyl    β-(3,5-dimethoxy-4-hydroxyphenyl)-α-(5-(2-methylpyridyl))ethylphosphonate;-   (E)-diethyl    β-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(3-pyridyl)vinylphosphonate;-   diethyl    β-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(3-pyridyl)ethylphosphonate;-   (E)-diethyl    β-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(5-(2-methylpyridyl))    vinylphosphonate;-   diethyl    β-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(5-(2-methylpyridyl))    ethylphosphonate;-   diisopropyl    β-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(5-(2-methylpyridyl))    ethylphosphonate;-   (E)-diethyl    β-(3,5-dimethoxy-4-hydroxyphenyl)-α-(4-(2-methylthiazolyl))vinylphosphonate;-   (E)-diethyl    β-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(4-(2-methylthiazolyl))    vinylphosphonate;-   (E)-diethyl    β-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(pyrazinyl)vinyl    phosphonate; and-   diethyl    β-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(pyrazinyl)ethylphosphonate.

One aspect of the present invention provides for a pharmaceuticalcomposition comprising a compound of formula (Ia) or formula (Ib) and apharmaceutically acceptable excipient. Hereinafter compounds of formula(Ia) and compounds of formula (Ib) are collectively termed “compounds offormula (I).”

The present invention also provides for therapeutic uses of thecompounds of formula (I). In one aspect, the invention provides for amethod of decreasing plasma levels of apo (a) and lipoprotein(a), inreducing plasma levels of apo B and LDL cholesterol and in decreasingplasma total cholesterol. The present invention also provides furthermethods including: a method of prevention and/or treatment of thrombosisby increasing thrombolysis through decreasing plasma levels of apo (a)and lipoprotein(a); a method of treatment of restenosis followingangioplasty by decreasing plasma levels of apo (a) and lipoprotein(a); amethod of prevention and/or treatment of atherosclerosis by decreasingplasma levels of apo (a) and lipoprotein(a) or by decreasing plasmalevels of apoprotein B and LDL cholesterol; a method of preventionand/or treatment of hypercholesterolemia; a method of prevention and/ortreatment of atherosclerosis by lowering cholesterol in patients thatare resistant to treatment with statins; and a method of preventionand/or treatment of atherosclerosis in association with a compound suchas a statin which decreases cholesterol synthesis.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to the compounds of formula (I) and theiruses for lowering plasma levels of apo (a), Lp(a), apo B, apo Bassociated lipoproteins (low density lipoproteins and very low densitylipoproteins) and for lowering plasma levels of total cholesterol.

In relation to compounds of formula (I), in preferred embodiments, X¹ ishydrogen, or methyl, X² is methoxy, ethoxy, methyl, tert-butyl orhydroxy, X³ is hydrogen, hydroxy, methoxy, methyl, ethyl orhydroxymethyl, X⁴ is hydrogen, methoxy, methyl or tert-butyl and X⁵ ishydrogen. In a preferred combination, X² is methoxy, X³ is hydroxy andX⁴ is methyl or methoxy. Preferably, n is zero, so that (B)_(n) isreplaced with a direct bond. Preferably R¹ and R² are C₁-C₃ alkyl, morepreferably C₂ or C₃, and in particular wherein R¹ and R² areindependently ethyl or isopropyl. Preferably m is zero or 1.

When used herein the term “heteroaryl” refers to, unless otherwisedefined, a single or a fused ring containing up to four heteroatoms ineach ring, each of which is selected from oxygen, nitrogen and sulphur,which rings may be unsubstituted or substituted by, for example, up tofour substituents. Each ring suitably has from 4 to 7, preferably 5 or 6ring atoms. A fused ring system may include carbocyclic rings and needinclude only one heteroaryl ring.

Representative examples of Het include pyridyl, pyrimidyl, pyrazinyl,pyridazinyl, thiazolyl, thiadiazolyl, benzothiazolyl, isoxazolyl,pyrazolyl, triazinyl, and imidazolyl which may be unsubstituted orsubstituted by up to four substituents (for pyridyl and benzothiazolyl),three substituents (pyrimidyl, pyrazinyl, pyridazinyl, pyrazolyl), twosubstituents (thiazolyl, isoxazolyl, triazinyl and imidazolyl) or onesubstituent (thiadiazolyl) which may be the same or different andselected from straight or branched C₁-C₄ alkyl or alkoxy, hydroxy,hydroxymethyl, halogen (F, Cl, Br, I), or an amino group optionallysubstituted with C₁-C₄ alkyl. Preferably, pyridyl, pyrimidyl, pyrazinyl,pyridazinyl, thiazolyl, thiadiazolyl, benzothiazolyl, pyrazolyl, ortriazinyl is unsubstituted or substituted by methyl, methoxy, dimethoxyor dimethyl. Preferred examples of Het include is pyrazinyl, 3-pyridyl,5-(2-methylpyridyl), 5-(2-methylthiazolyl) pyridyl).

Pharmaceutically acceptable salts for use in the present inventioninclude those described by Berge, Bighley, and Monkhouse, J. Pharm.Sci., 1977, 66, 1-19. Such salts may be formed from inorganic andorganic acids. Representative examples thereof include maleic, fumaric,benzoic, ascorbic, parnoic, succinic, bismethylenesalicylic,methanesulfonic, ethanedisulfonic, acetic, propionic, tartaric,salicylic, citric, gluconic, aspartic, stearic, palmitic, itaconic,glycolic, p-aminobenzoic, glutamic, benzenesulfonic, hydrochloric,hydrobromic, sulfuric, cyclohexylsulfamic, phosphoric and nitric acids.

It will be appreciated that certain compounds of the present invention,in particular those of formula (Ia), will comprise one or more chiralcentres so that compounds may exist as stereoisomers, includingdiastereoisomers and enantiomers. The present invention covers all suchstereoisomers, and mixtures thereof, including racemates. The compoundsof formula (Ib) of the present invention comprise the individual E- andZ-diastereoisomers and mixtures thereof.

Since the compounds of the present invention are intended for use inpharmaceutical compositions, it will be understood that they are eachprovided in substantially pure form, for example at least 50% pure, moresuitably at least 75% pure and preferably at least 95% pure (% are on awt/wt basis). Impure preparations of the compounds of formula (I) may beused for preparing the more pure forms used in the pharmaceuticalcompositions. Although the purity of intermediate compounds of thepresent invention is less critical, it will be readily understood thatthe substantially pure form is preferred as for the compounds of formula(I). Preferably, whenever possible, the compounds of the presentinvention are obtained in crystalline form.

When some of the compounds of this invention are allowed to crystalliseor are recrystallised from organic solvents, solvent of crystallisationmay be present in the crystalline product. This invention includeswithin its scope such solvates. Similarly, some of the compounds of thisinvention may be crystallised or recrystallised from solvents containingwater. In such cases water of hydration may be formed. This inventionincludes within its scope stoichiometric hydrates as well as compoundscontaining variable amounts of water that may be produced by processessuch as lyophilisation. In addition, different crystallisationconditions may lead to the formation of different polymorphic forms ofcrystalline products. This invention includes within its scope allpolymorphic forms of the compounds of formula (I).

The present invention also relates to the unexpected discovery thatcompounds of formula (I) are effective for decreasing apo(a) productionin vitro and Lp(a) production in vivo in Cynomolgus monkeys. Thisspecies has been selected as the animal model as its Lp(a) is similar inimmunologic properties to human Lp(a) and occurs in almost identicalfrequency distribution of plasma concentrations, see e.g., N. Azrolan etal; J. Biol. Chem., 266, 13866-13872 (1991). In the ill vitro assay,compounds of formula (I) have been shown to reduce the secretion of apo(a) which is secreted in free form from the primary cultures of theCynomolgus monkey hepatocytes. These results are confirmed by the invivo studies performed on the same animal species showing the potentdecrease of Lp(a) by compounds of formula (I). Therefore the compoundsof this invention are useful for decreasing apo (a) and Lp(a) in man andthus provide a therapeutic benefit.

Accordingly in a further aspect, this invention provides a compound offormula (I) or a pharmaceutically acceptable salt thereof for use intherapy, in particular as a Lp(a) lowering agent. Elevated plasma andtissue levels of Lp(a) are associated with accelerated atherosclerosis,abnormal proliferation of smooth muscle cells and increasedthrombogenesis and expressed in disease states such as, for instance:coronary heart disease, peripheral artery disease, intermittentclaudication, thrombosis, restenosis after angioplasty, extra-cranialcarotid atherosclerosis, stroke and atherosclerosis occurring afterheart transplantion.

Furthermore, the compounds of the present invention may possesscholesterol lowering properties and decrease total plasma cholesterol,in particular LDL cholesterol. It is now well established that a highlevel of LDL cholesterol is a major risk factor for atheroscleroticdiseases. In addition, the compounds of the present invention maydecrease the levels of apoprotein B (apo B) which is the main protein ofLDL and the main ligand for LDL receptors. The mechanism of decrease inapo B and in apo B-associated LDL probably does not involve inhibitionof cholesterol synthesis, which is the mechanism demonstrated for thestatins. Therefore, compounds of the present invention are useful forlowering cholesterol in patients who are resistant to treatment with astatin, and, conversely, also have an additive or synergistic effect forlowering cholesterol in those patients who are responding to treatmentwith statins.

Thus, compounds of the present invention are of use in therapy ascholesterol lowering agents. Furthermore, a dual profile in loweringplasma Lp(a) and plasma cholesterol makes the compounds of formula (I)useful in therapy for the prevention and/or treatment of both the acuteand chronic aspects of atherosclerosis.

Compounds of the present invention may also be of use in preventingand/or treating the above-mentioned disease states in combination withanti-hyperlipidaemic, anti-atherosclerotic, anti-diabetic, anti-anginal,anti-inflammatory or anti-hypertension agents. Examples of the aboveinclude cholesterol synthesis inhibitors such as statins, for instanceatorvastatin, simvastatin, pravastatin, cerivastatin, fluvastatin,lovastatin and ZD 4522 (also referred to as S-4522′, Astra Zeneca),anti-oxidants such as probucol, insulin sensitisers such as a PPAR gammaactivator, for instance G1262570 (Glaxo Wellcome) and the glitazoneclass of compounds such as rosiglitazone (Avandia, SmithKline Beecham),troglitazone and pioglitazone, calcium channel antagonists, andanti-inflammatory drugs such as NSAIDs.

For therapeutic use the compounds of the present invention willgenerally be administered in a standard pharmaceutical composition.Accordingly in a further aspect, the invention provides for apharmaceutical composition comprising a compound of formula (I) or apharmaceutically acceptable salt thereof and a pharmaceuticallyacceptable excipient or carrier. Suitable excipients and carriers arewell known in the art and will be selected with regard to the intendedroute of administration and standard pharmaceutical practice. Forexample, the compositions may be administered orally in the form oftablets containing such excipients as starch or lactose, or in capsules,ovules or lozenges either alone or in admixture with excipients, or inthe form of elixirs or suspensions containing flavoring or coloringagents. They may be injected parenterally, for example, intravenously,intramuscularly or subcutaneously. For parenteral administration, theyare best used in the form of a sterile aqueous solution which maycontain other substances, for example, enough salts or glucose to makethe solution isotonic with blood. The choice of form for administrationas well as effective dosages will vary depending, inter alia, on thecondition being treated. The choice of mode of administration and dosageis within the skill of the art.

The compounds of formula (I) and their pharmaceutically acceptable saltswhich are active when given orally can be formulated as liquids, forexample syrups, suspensions or emulsions or as solids for example,tablets, capsules and lozenges. A liquid formulation will generallyconsist of a suspension or solution of the compound or pharmaceuticallyacceptable salt in suitable liquid carrier(s) for example, ethanol,glycerine, non-aqueous solvent, for example polyethylene glycol, oils,or water with a suspending agent, preservative, flavoring or coloringagents. A composition in the form of a tablet can be prepared using anysuitable pharmaceutical carrier(s) routinely used for preparing solidformulations. Examples of such carriers include magnesium stearate,starch, lactose, sucrose and cellulose. A composition in the form of acapsule can be prepared using routine encapsulation procedures. Forexample, pellets containing the active ingredient can be prepared usingstandard carriers and then filled into a hard gelatin capsule;alternatively, a dispersion or suspension can be prepared using anysuitable pharmaceutical carrier(s), for example aqueous gums,celluloses, silicates or oils and the dispersion or suspension thenfilled into a soft gelatin capsule.

Typical parenteral compositions consist of a solution or suspension ofthe compound or pharmaceutically acceptable salt in a sterile aqueouscarrier or parenterally acceptable oil, for example polyethylene glycol,polyvinyl pyrrolidone, lecithin, arachis oil or sesame oil.Alternatively, the solution can be lyophilised and then reconstitutedwith a suitable solvent just prior to administration. A typicalsuppository formulation comprises a compound of structure (I) or apharmaceutically acceptable salt thereof which is active whenadministered in this way, with a binding and/or lubricating agent suchas polymeric glycols, gelatins or cocoa butter or other low meltingvegetable or synthetic waxes or fats. Preferably the composition is inunit dose form such as a tablet or capsule.

Each dosage unit for oral administration contains preferably from 1 to250 mg (and for parenteral administration contains preferably from 0.1to 25 mg) of a compound of formula (I) or a pharmaceutically acceptablesalt thereof calculated as the free base.

The compounds of the invention will normally be administered to asubject in a daily dosage regimen. For an adult patient this may be, forexample, an oral dose of between 1 mg and 500 mg, preferably between 1mg and 250 mg, or an intravenous, subcutaneous, or intramuscular dose ofbetween 0.1 mg and 100 mg, preferably between 0.1 mg and 25 mg, of thecompound of the formula (I) or a pharmaceutically acceptable saltthereof calculated as the free base, the compound being administered 1to 4 times per day.

The present invention also relates to processes for preparing novelα-substituted heteroarylalkylphosphonate derivatives of formula (I),which is described below.

Compounds of formula (Ib) may be prepared by a process which comprisescondensing an aldehyde of formula (II):

in which X¹, X², X³, X¹, X⁵, B and n are as previously defined; with anheteroarylalkylphosphonate of formula (III):

in which m, R¹, R² and Het are as previously defined,

The condensation reaction between (II) and (III) can be carried out inseveral ways. In the first variant the α-silyl carbanion of theheteroarylalkyl phosphonate (III) is condensed with the aldehyde (II)under the conditions of the Peterson olefination reaction. Suitablesilylating reagents include chlorotrimethylsilane orchlorotriethylsilane. A preferred silylating agent ischlorotrimethylsilane. Suitably, the condensation may be carried out inan ether solvent such as diethyl ether, tetrahydrofuran (TBF),dimethoxyethane or dioxane. A preferred solvent is THF. Suitable basesinclude n-butyllithium, lithium diisopropylamide (LDA) formed in situ byreacting n-butyllithium and diisopropylamine, or n-butyllithium used inassociation with N,N,N′,N′-tetramethylethylenediamine The reaction issuitably carried out in the range from −78° C. to room temperature (20°C.).

Another variant consists in reacting the carbanion of theheteroarylalkyldiphosphonate (IV):

with the aldehyde (II) under the Horner-Emmons olefination reaction.Suitably, the condensation may be carried out in an ether solvent suchas diethyl ether, tetrahydrofuran (THF), dimethoxyethane, dioxane, ordimethylformamide (DMF). A preferred solvent is THF. Suitable basesinclude sodium hydride, n-butyllithium, lithium diisopropylamide (LDA)formed in situ by reacting n-butyllithium and diisopropylamine, orn-butyllithium used in association withN,N,N′,N′-tetramethylethylenediamine. The reaction is suitably carriedout in the range from −78° C. to room temperature (20° C.).

Both of these two mentioned variants of the condensation of aheteroarylalkylphosphonate of formula (II) or aheteroarylalkyldiphosphonate of formula (IV) with an aldehyde of formula(II) afford compounds of formula (Ib^(Z)) and (Ib^(E)). The two isomers(Ib^(Z)) and (Ib^(E)) can be separated by column chromatography. Thestructures of these isomers are ascertained by spectroscopic means: MSand in particular NMR, thanks to the characteristic absorption of theolefinic proton. In the (Z)-isomer (Ib^(Z)), the olefinic protondisplays a large coupling constant, J=ca 40-43 Hz, due to the transH—C═C—P coupling. In the (E)-isomer (Ib^(E)) this value is much smaller,J=ca 25 Hz, due to the cis H—C═C—P coupling.

Compounds of formula (Ia) can be prepared by reducing compounds offormula (Ib) or, very conveniently, a mixture of both.

A suitable reduction method is the catalytic hydrogenation using ascatalysts palladium or platinum adsorbed on charcoal in a solvent suchas ethanol or acetic acid at a pressure between 1 and 4 atm and atemperature between room temperature and 40° C. The reduction can alsobe carried out by means of a complex hydride reagent such as sodiumborohydride or sodium cyanoborohydride in a polar solvent such asmethanol, ethanol, isopropanol or n-propanol at a temperature betweenroom and reflux temperature. A further convenient reduction method isthe use of a zinc modified sodium cyanoborohydride reagent generatedfrom a mixture of NaBH₃CN:ZnCl₂ in a 2:1 molar ratio in a solventselected from diethyl ether, tetrahydrofuran, dimethoxyethane andmethanol at a temperature between room temperature and refluxtemperature; the reaction can be accelerated by the addition of a higherboiling solvent selected from ethanol, isopropanol, n-propanol,isobutanol or n-butanol and heating to reflux the resulting mixture.

In a further variant, compound (Ia) can be directly obtained by thereaction between the heteroarylalkylphosphonate (III) and an alkylhalide of formula (V), wherein the Hal is chloro or bromo, in presenceof a base.

Suitable solvents include diethyl ether, tetrahydrofuran (THF),dimethoxyethane or dioxane. A preferred solvent is THF. Suitable basesinclude n-butyllithium, lithium diisopropylamide (LDA) formed in situ byreacting n-butyllithium and diisopropylamine, or n-butyllithium used inassociation with TMEDA (N,N, N′,N′-tetramethylethylenediamine). Thereaction is suitably carried out in the range from −78° C. to roomtemperature (20° C.).

When any of the substituents X¹, X², X³, X⁴ or X⁵, is a hydroxy group,giving a reactive phenol or hydroxymethylphenyl group, it may be usefulto protect such a hydroxy group, to avoid troublesome side reactionswhich may otherwise occur under the strongly alkaline reactionconditions employed. A particularly effective way of protecting the OHgroup is to convert it into an alkyl silyl ether, such as trimethylsilyl ether (Me₃Si ether or Tms ether) or a t-butyldimethyl silyl ether(tBuMe₂Si ether or Tbs ether). An integral part of this invention is theconversion of the aldehyde of formula (II) or the halide of formula (V)comprising a hydroxy group into the corresponding Tbs ether. Suitableprotection reaction conditions are the use of t-butyldimethylsilylchloride in presence of imidazole in dimethylformamide. Such an Tbsprotected aldehyde (II) or halide (V) can then withstand the stronglyalkaline conditions which are necessary to form the desiredTbs-protected (Ia) or (Ib) structures. The Tbs protecting group can thenbe cleaved by fluoride reagents well established in the art to yield theend products of formula (I) wherein any of the substituents X¹, X², X³.X⁴ or X⁵ can be a hydroxy group. Suitable deprotection reactionconditions involve reacting the Tbs protected compound with tetrabutylammonium fluoride in glacial acetic acid.

The various starting compounds heteroarylalkylphosphonates (III),heteroarylalkyldiphosphonates (IV), aldehydes (II) and halide (V) can beprepared according to methods described in the chemical literature.

EXAMPLES OF THE INVENTION

The invention is further described in the following examples that areintended to illustrate the invention without limiting its scope. Theabbreviations used in this application are the following: in the tables,n is normal, i is iso, s is secondary and t is tertiary. In thedescription of the NMR spectra, respectively s is singlet, d doublet, dddouble doublet, t triplet, q quadruplet and m multiplet. Thetemperatures were recorded in degrees Celsius and the melting points arenot corrected.

The structures of compounds described in the Examples were establishedby their infrared (IR), mass (MS) and nuclear magnetic resonance (NMR)spectra. The purity of the compounds was checked by thin layer, gas,liquid or high performance liquid chromatography.

Unless otherwise indicated, the physical constants and biological datagiven for compounds of formula (Ia) refer to racemates while those givenfor compounds of formula (Ib^(E)) and (Ib^(Z)) refer to pure isomers.

Example 1 (E)-Diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(3-pyridyl)-vinyl Phosphonate

60% NaH (8.63 g, 216 mmol) was washed three times with hexane and wassuspended in 60 ml THF. This suspension was cooled to 0° and diethylphosphite (27.8 ml, 216 mmol) was added dropwise. 30 Minutes after theend of the addition a solution of 3-chloromethylpyridine (13.8 g, 108mmol) in 60 ml THF was added dropwise and the ice bath was removed. H₂O(40 ml) was added dropwise after stirring at room temperature for 4 h,then sat. NH₄Cl solution (40 ml) was added in one portion. The aqueousphase was separated and extracted with CHCl₃ (3 portions of 200 ml). Thecombined organic layers were dried with MgSO₄ and evaporated to give25.8 g of a brown oil. Purification of this crude product by columnchromatography (CHCl₃/MeOH 9/1) yielded 20.5 g (89 mmol, 82%) of a brownoil; GC-analysis indicated a purity of 97%.

The whole procedure was carried out at −78° C. and under a nitrogenatmosphere. Diisopropylamine (37.8 ml, 268 mmol) was added dropwise to asolution of nBuLi 1.6 M (168 ml, 268 mmol) in 650 ml THF. After 30 min.a solution of diethyl 3-pyridylmethylphosphonate (20.5 g, 89 mmol) in 50ml THF was added dropwise. After 30 min of stirring trimethylchlorosilane (22.5 ml, 178 mmol) was added dropwise, the reactionmixture was stirred for a further 30 min then a solution of4-t-butyldimethylsilyloxy-3-methoxy-5-methylbenzaldehyde (25 g, 89 mmol)in 50 ml THF was added dropwise. The reaction mixture was stirred at−78° for 2 h, then the cooling bath was removed and sat. NH₄Cl-solution(300 ml) was added in one portion. The mixture was allowed to warm toroom temperature and the aqueous phase was separated and extracted withether (one 800 ml and three 500 ml portions). The combined organiclayers were dried with MgSO₄ and evaporated to give 45 g of a brown oil.Purification of this crude product by flash chromatography (AcOEt/MeOH9/1) yielded 31 g (63 mmol, 70%) of (E)-diethylβ-(4-t-butyldimethylsilyloxy-3-methoxy-5-methylphenyl)-α-(3-pyridyl)-vinylphosphonateas a brown oil.

A solution of tetrabutylammonium fluoride (79.5 g, 252 mmol) in 250 mlTBF was added in four portions to a solution of the preceding compound(31 g, 63 mmol) in 250 ml THF and 67 ml acetic acid. The reactionsolution was stirred at room temperature for 3 h and was partitionedbetween 800 ml CH₂Cl₂ and 200 ml H₂O. The organic phase was separatedand washed with three portions of 300 ml sat. NaHCO₃ solution. Theorganic layer was dried with MgSO₄ and evaporated to give 23.8 g of abrown oil. Purification of this crude product by flash chromatography(AcOEt/MeOH 9/1) yielded 18 g (47.7 mmol, 75%) of the title compound asa white solid, mp=102-103° C.

MS (m/e)=377: M⁺, 239 (100%): M⁺—HPO₃Et₂ NMR (CDCl₃): δ=8.58, 8.51, 7.66and 7.34 (4m, H each): aromatic H, 3-pyridyl 7.6: (d, 1H, J=24 Hz):(Ph)(CH)C═C(P)-pyridine 6.61 and 6.23 (2m, 1H each): aromatic H,substituted phenyl 5.30 (s, 1H): OH 4.16-4.06 (m, 4H): P—O—CH ₂—CH₃ 3.47(s, 6H): Ph-OCH ₃ 2.12 (1s, 3H): Ph-CH ₃ 1.29 (2t, J=7 Hz, 6H):P—O—CH₂—CH ₃

Example 2 Diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(3-pyridyl)-ethylphosphonate

A solution of (E)-diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(3-pyridyl)vinylphosphonate (18g, 47.7 mmol) in 400 ml ethanol was hydrogenated over 9 g of 10% Pd/Ccatalyst in a Parr hydrogenation apparatus at an initial pressure of 50psi. When hydrogen uptake has ceased, the catalyst was filtered off, thesolvent was evaporated to give 17 g of slightly yellow solid.Purification of this crude product by recrystallisation from a mixtureof ligroine and CH₂Cl₂ yielded 13 g (34 mmol, 72%) of a white solid,mp=85-87° C. GC-analysis indicated a purity of 100%.

MS (m/e)=379: M⁺, 241 (100%): M⁺—HPO₃Et₂ NMR (CDCl₃): δ=8.45, 8.38, 7.70and 7.22 (4m, 1H each): aromatic H, 3-pyridyl 6.39 and 6.21 (2d, 1Heach, J=1.5 Hz): aromatic H, substituted phenyl 5.30 (s, 1H): OH4.11-3.82 (3m, 4H total): P—O—CH ₂—CH₃ 3.67 (s, 3H): Ph-OCH ₃ 3.44-3.36(m, H): Ph-CH₂—CH(P)-pyridine 3.3-3.2 and 3.07-2.97 (2m, 1H each): Ph-CH₂—CH(P)-pyridine 2.12 (1s, 3H): Ph-CH ₃ 1.30 and 1.15 (2t, J=7 Hz, 3Heach): P—O—CH₂—CH ₃

Example 3 (E)-Diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(5-(2-methylpyridyl))-vinylphosphonate

5-Chloromethyl-2-methylpyridine hydrochloride (15 g, 87.3 mmol) wassuspended in 100 ml CH₂Cl₂ and a 10% NaOH solution was added whilestirring until the pH of the aqueous phase was 8. The mixture was shakenthen the CH₂Cl₂ phase was separated, dried over MgSO4 and evaporated toyield 11.9 g (100%) of the free base. 60% NaH (10.63 g, 440 mmol) waswashed three times with hexane and was suspended in 100 ml THF. Thissuspension was cooled to 0° and diethyl phosphite (38.3 ml, 280 mmol)was added dropwise. 30 Minutes after the end of the addition a solutionof 5-chloromethyl-2-methylpyridine (17.9 g, 120 mmol) in 10 ml THF wasadded dropwise and the ice bath was removed. The reaction was stirredfor 4 h at room temperature then H₂O (100 ml) was added dropwise, thensat. NH₄Cl solution (100 ml) was added in one portion. The aqueous phasewas separated and extracted with CHCl₃ (3 portions of 200 ml). Thecombined organic layers were dried with MgSO₄ and evaporated to give25.8 g of a brown oil. Purification of this crude product by columnchromatography (CHCl₃/MeOH 95/5) yielded 21.5 g (73%) of diethyl5-(2-methylpyridyl)methylphosphonate as a brown oil.

The whole procedure was carried out at −78° C. and under a nitrogenatmosphere. Diisopropylamine (2.96 ml, 21 mmol) was added dropwise to asolution of nBuLi 1.6 M (13.2 ml, 21 mmol) in 80 ml THF. After 30 min. asolution of diethyl 5-(2-methylpyridyl)methylphosphonate (1.7 g, 7 mmol)in 100 ml THF was added dropwise. After 30 min of stirring trimethylchlorosilane (1.77 ml, 14 mmol) was added dropwise, the reaction mixturewas stirred for a further 30 min then a solution of4-t-butyldimethylsilyloxy-3-methoxy-5-methylbenzaldehyde (1.96 g, 7mmol) in 10 ml THF was added dropwise. The reaction mixture was stirredat −78° for 2 h, then the cooling bath was removed and sat.NH₄Cl-solution (100 ml) was added in one portion. The mixture wasallowed to warm to room temperature and the aqueous phase was separatedand extracted with ether (one 200 ml and three 100 ml portions). Thecombined organic layers were dried with MgSO₄ and evaporated to give 2.5g of a brown oil. Purification of this crude product by columnchromatography (AcOEt/MeOH 9/1) yielded 1.3 g (2.5 mmol, 35%) of(E)-diethylβ-(4-t-butyldimethylsilyloxy-3-methoxy-5-methylphenyl)-α-(5-(2-methylpyridyl))-vinylphosphonateas a brown oil.

A solution of tetrabutylammonium fluoride (2.25 g, 7.13 mmol) in 30 mlTHF was added in four portions to a solution of the preceding compound(1.3 g, 2.5 mmol) in 20 ml THF and 1.2 ml acetic acid. The reactionsolution was stirred at room temperature for 3 h and was partitionedbetween 500 ml CH₂Cl₂ and 100 ml H₂O. The organic phase was separatedand washed with three portions of 300 ml sat. NaHCO₃ solution. Theorganic layer was dried with MgSO₄ and evaporated to give 2.1 g of abrown oil. Purification of this crude product by flash chromatography(AcOEt/MeOH 9/1) yielded 0.78 g (19.9 mmol, 79%) of the title compoundas an oil which slowly crystallized.

MS (m/e)=391: M⁺, 253 (100%): M⁺—HPO₃Et₂ NMR (CDCl₃): δ=8.39, 7.52 and7.20 (3m, H each): aromatic H, 3-pyridyl 7.58: (d, 1H, J=24 Hz):(Ph)(CH)C═C(P)-pyridine 6.62 and 6.28 (2m, 1H each): aromatic H,substituted phenyl 5.89 (s, 1H): OH 4.16-4.06 (m, 4H): P—O—CH ₂—CH₃ 3.50(s, 6H): Ph-OCH ₃ 2.49 (s, 3H): Py-CH ₃ 2.12 (1s, 3H): Ph-CH ₃ 1.29 (2t,J=7 Hz, 6H): P—O—CH₂—CH₃

Example 4 Diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(3-pyridyl)-ethylphosphonate

A solution of (E)-diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(5-(2-methylpyridyl))vinylphosphonate(0.45 g, 1.15 mmol) in 80 ml ethanol was hydrogenated over 0.2 g of 10%Pd/C catalyst in a Parr hydrogenation apparatus at an initial pressureof 50 psi. When hydrogen uptake has ceased, the catalyst was filteredoff, the solvent was evaporated to give 0.6 g of a yellow oil.Purification of this crude product by column chromatography (AcOEt/MeOH9/1) yielded 0.3 g (0.76 mmol, 66%) of a white solid, mp=68-70° C.

MS (m/e)=393: M⁺, 255 (100%): M⁺—HPO₃Et₂ NMR (CDCl₃): δ=8.35, 7.59 and7.08 (4m, 1H each): aromatic H, 3-pyridyl 6.39 and 6.22 (2d, 1H each,J=1.5 Hz): aromatic H, substituted phenyl 5.55 (s, 1H): OH 4.11-3.82(3m, 4H total): P—O—CH ₂—CH₃ 3.67 (s, 3H): Ph-OCH ₃ 3.42-3.35 (m, H):Ph-CH₂—CH(P)-pyridine 3.29-3.2 and 3.05-2.97 (2m, 1H each): Ph-CH₂—CH(P)-pyridine 2.50 (s, 3H): Py-CH ₃ 2.12 (1s, 3H): Ph-CH ₃ 1.30 and1.15 (2t, J=7 Hz, 3H each): P—O—CH₂—CH ₃

Example 5 (E)-Diethyl β-(3-ethoxy-4-hydroxyphenyl)-α-(3-pyridyl)-vinylPhosphonate

4-t-Butyldimethylsilyloxy-3-ethoxybenzaldehyde (2.69 g, 9.61 mmol) wasprepared by reacting 3-ethoxy-4-hydroxybenzaldehyde (1.62 g, 9.7 mmol)with t-butyldimethylsilyl chloride (2.20 g, 14.6 mmol) in 40 ml DMF inpresence of imidazole (2.19 g, 32.2 mmol). The whole procedure wascarried out at −78° C. and under a nitrogen atmosphere. Diisopropylamine(3.4 ml, 24 mmol) was added dropwise to a solution of nBuLi 1.6 M (15ml, 24 mmol) in 100 ml TBF. After 30 min. a solution of diethyl3-pyridylmethylphosphonate (2.20 g, 9.61 mmol) in 10 ml TBF was addeddropwise. After 30 min of stirring trimethyl chlorosilane (1.82 ml, 14.4mmol) was added dropwise, the reaction mixture was stirred for a further30 min then a solution of 4-t-butyldimethylsilyloxy-3-ethoxybenzaldehyde(2.69 g, 9.61 mmol) in 10 ml THF was added dropwise. The reactionmixture was stirred at −78° for 2 h, then the cooling bath was removedand saturated NH₄Cl-solution (100 ml) was added in one portion. Themixture was allowed to warm to room temperature and the aqueous phasewas separated and extracted with ether. The combined organic layers weredried with MgSO₄ and evaporated to give 6.0 g of a brown oil.Purification of this crude product by column chromatography (CH₂Cl₂/MeOH95/5) yielded 1.7 g (3.46 mmol, 36%) of (E)-diethylβ-(4-t-butyldimethylsilyloxy-3-ethoxyphenyl)-α-(3-pyridyl)-vinylphosphonateas a brown oil.

A solution of tetrabutylammonium fluoride (2.25 g, 7.13 mmol) in 30 mlTBF was added in four portions to a solution of the preceding compound(1.7 g, 3.46 mmol) in 20 ml TBF and 1.2 ml acetic acid. The reactionsolution was stirred at room temperature for 3 h and was partitionedbetween CH₂Cl₂ and H₂O. The organic phase was separated and washed withthree portions of saturated NaHCO₃ solution. The organic layer was driedwith MgSO₄ and evaporated to give 1.8 g of a brown oil. Purification ofthis crude product by column chromatography (CH₂Cl₂/MeOH 95/5) yielded0.51 g (1.35 mmol, 39%) of the title compound as an oil which slowlycrystallized.

MS (m/e)=377: M⁺, 239 (100%): M⁺—HPO₃Et₂ NMR (CDCl₃): δ=8.59, 8.51, 7.65and 7.35 (4m, H each): aromatic H, 3-pyridyl 7.62: (d, 1H, J=24 Hz):(Ph)(CH)C═C(P)-pyridine 6.77, 6.70 and 6.4 (3m, 1H each): aromatic H,substituted phenyl 6.15 (broad peak, 1H): OH 4.16-4.06 (m, 4H): P—O—CH₂—CH₃ 3.67 (q, J=7 Hz, 4H): PhO-CH ₂—CH₃ 1.29 (2t, J=7 Hz, 6H):P—O—CH₂—CH ₃ 1.27 (t, J=7 Hz, 3H): PhO-CH₂—CH ₃

Example 6 (E)-Diethylβ-(3-ethoxy-4-hydroxyphenyl)-α-(3-pyridyl)-ethylphosphonate

A solution of (E)-diethylβ-(3-ethoxy-4-hydroxyphenyl)-α-(3-pyridyl)vinylphosphonate (0.51 g, 1.38mmol) in 80 ml ethanol was hydrogenated over 0.2 g of 10% Pd/C catalystin a Parr hydrogenation apparatus at an initial pressure of 50 psi. Whenhydrogen uptake has ceased, the catalyst was filtered off, the solventwas evaporated to give 0.49 g (95%) of a yellow oil which slowlysolidified.

MS (m/e)=379: M⁺, 241 (100%): M⁺—HPO₃Et₂ NMR (CDCl₃): δ=8.45, 8.37, 7.68and 7.22 (4m, 1H each): aromatic H, 3-pyridyl 6.70, 6.48 and 6.37 (3m,1H each): aromatic H, substituted phenyl 5.65 (s, 1H): OH 4.15-3.82 (3m,4H total): P—O—CH ₂—CH₃ and PhO-CH ₂—CH₃ 3.47-3.39 (m, 1H):Ph-CH₂—CH(P)-pyridine 3.3-3.2 and 3.09-3.0 (2m, 1H each): Ph-CH₂—CH(P)-pyridine 1.34 and 1.15 (2t, J=7 Hz, 3H each): P—O—CH₂—CH ₃ 1.30(t, 3H): PhO-CH₂—CH ₃

Example 7 Diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(2-pyrazinyl)-ethylphosphonate

2-Chloromethylpyrazine was prepared by chlorination of 2-methylpyrazineby N-chlorosuccinimide in presence of dibenzoylperoxide in CCl₄according to a literature method. The crude compound thus obtained wasused directly for the next step. 60% NaH (4.36 g, 109 mmol) was washedthree times with hexane and was suspended in 27 ml THF. This suspensionwas cooled to 0° and diethyl phosphite (14 ml, 109 mmol) was addeddropwise. 30 Minutes after the end of the addition a solution of2-chloromethylpyrazine (9.67 g, 75 mmol) in 40 ml THF was added dropwiseand the ice bath was removed. The reaction was stirred for 4h then H₂O(20 ml) was added dropwise then a saturated NH₄Cl solution (20 ml) wasadded in one portion. The aqueous phase was separated and extracted withCHCl₃ (two 200 ml portions). The combined organic layers were dried withMgSO₄ and evaporated to give 16.8 g of a brown oil. Purification of thiscrude product by flash chromatography (CH₂Cl₂/MeOH 49:1, then 19:1)yielded 5.65 g (24.5 mmol, 33%) of diethyl 2-pyrazinylmethylphosphonateas a brown oil.

Diisopropyl amine (5.1 ml, 36 mmol) was added dropwise to a solution ofnBuLi 1.6 M (22.5 ml, 36 mmol) in 130 ml TBF. After 30 min. a solutionof diethyl 2-pyrazinylmethylphosphonate (2.75 g, 11.9 mmol) in 7 ml THFwas added dropwise (int. temp.≦−70°). After 0.5 h TMSCl (3.0 ml, 23.7mmol) was added dropwise (int. temp.≦−70°), further 30 min. later asolution of 4-t-butyldimethylsilyloxy-3-methoxy-5-methylbenzaldehyde(3.35 g, 11.9 mmol) in 9 ml THF was added dropwise (int. temp.≦−70°).The reaction mixture was stirred at −78° for 2 h, then the cooling bathwas removed and a saturated NH₄Cl solution (50 ml) was added in oneportion. The mixture was allowed to warm to room temperature and theaqueous phase was separated and extracted with ether (one 800 ml andthree 300 ml portions). The combined organic layers were dried withMgSO₄ and evaporated to give 6.36 g of a brown oil. Purification of thiscrude product by flash chromatography (AcOEt, then AcOEt/MeOH 19:1)yielded 2.0 g (4.06 mmol, 34%) of diethylβ-(4-t-butyldimethylsilyloxy-3-methoxy-5-methylphenyl)-α-(2-pyrazinyl)-vinylphosphonateas a brown oil.

A solution of tetrabutylammonium fluoride (320 mg, 1.01 mmol) in 27 mlTBF was added in one portion to a solution of the preceding compound(2.00 g, 4.06 mmol) in 27 ml TBF. The reaction solution was stirred atroom temperature for 3 h and was partitioned between 240 ml CH₂Cl₂ and18 ml H₂O. The organic phase was separated and washed with 300 mlsaturated NaHCO₃ solution. The organic layer was dried with MgSO₄ andevaporated to give 1.70 g of a brown oil. Purification of this crudeproduct by flash chromatography (AcOEt, then AcOEt/MeOH 49:1) yielded1.05 g (2.78 mmol, 68%) diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(2-pyrazinyl)-vinylphosphonateas a light brown oil.

MS (m/e): 378: M⁺, 241: M⁺—PO₃Et₂ ¹H-NMR (CDCl₃): δ=8.68 (t, 3=1.9 Hz,1H): aromatic H, pyrazinyl 8.52 (m, 2H): aromatic H, pyrazinyl 7.78 and7.73 (2s, 1H total): olefinic H (cis+trans) 6.49 and 6.17 (2d, J=1.3 Hzand J=1.8 Hz, 2H total): aromatic H, subst. phenyl 5.88 (s, 1H): OH4.21-4.08 (m, 4H): P—O—CH ₂—CH₃ 3.54 (s, 3H): Ph-OCH₃ 2.10 (s, 3H):Ph-CH₃ 1.33 and 1.28 (m, 6H total): P—O—CH₂—CH ₃

A solution of the preceding compound (830 mg, 2.19 mmol) in 150 mln-propanol was added in one portion to a solution of NaBH₃CN (1.65 g,26.3 mmol) and ZnCl₂ (1.79 g, 13.1 mmol) in 50 ml MeOH. The reactionsolution was heated to reflux and methanol was gradually evaporateduntil the boiling point of the remaining suspension reached 85°. The oilbath temperature was reduced to 90° and stirring was continued for 21 h.The reaction mixture was concentrated to about half its volume and theremaining suspension was partitioned between CHCl₃ and 10% NaOH. Theaqueous phase was separated and extracted with CHCl₃. The combinedorganic layers were washed with H₂O, dried with MgSO₄ and evaporated togive 740 mg of a brown oil. Purification of this crude product by flashchromatography (AcOEt/MeOH 49:1, then 19:1) yielded 464 mg (1.22 mmol,56%) of the title compound as an oil which slowly crystallized.

MS (m/e): 380: M⁺, 243: M⁺—PO₃Et₂ ¹H-NMR (CDCl₃): δ=8.53 (m, 1H):aromatic H, pyrazinyl 8.45 (t, J=1.6 Hz, 1H): aromatic H, pyrazinyl 8.39(t, 3=2.3 Hz, 1H): aromatic H, pyrazinyl 6.42 and 6.33 (2d, J=1.4 Hz and1.8 Hz, 2H total): aromatic H, substituted phenyl 5.53 (s, 1H): OH4.19-4.00 (m, 4H): P—O—CH ₂—CH₃ 3.71 (s, 3H): Ph-OCH₃ 3.68-3.60 (m, 1H):(Ph)CH₂—CH(P) 3.44-3.31 (m, 2H): (Ph)CH ₂—CH(P) 2.11 (s, 3H): Ph-CH ₃1.30 and 1.24 (2 t, J=7.1 Hz, 6H total): P—O—CH₂—CH ₃

Example 8 (E)- and (Z)-Diethyl β-(3-methoxyphenyl)-α-(3-pyridyl)-vinylPhosphonate

(Z)-Diethyl β-(3-methoxyphenyl)-α-3-pyridyl)-vinyl Phosphonate

(E)-Diethyl β-(3-methoxyphenyl)-α-(3-pyridyl)-vinyl phosphonatediisopropylamine (7.72 ml, 54.6 mmol) was added dropwise to a solutionof nBuLi 1.6 M (34.1 ml, 54.6 mmol) in 150 ml THF. After 30 min. asolution of diethyl 3-pyridylmethylphosphonate (5.0 g, 21.83 mmol) in 10ml THF was added dropwise (int. temp.≦−70°). After 0.5h TMSCl (4.13 ml,32.75 mmol) was added dropwise (int. temp.≦−70°), further 30 min. latera solution of 3-methoxybenzaldehyde (3.56 g, 26.2 mmol) was addeddropwise (int. temp.≦−70°). The reaction mixture was stirred at −78° for2 h, then the cooling bath was removed and sat. NH₄Cl-solution wasadded. The mixture was allowed to come to room temperature and theaqueous phase was separated and extracted with ether. The combinedorganic layers were dried with MgSO₄ and evaporated to give 8.5 g of abrown oil. Purification of this crude product by flash chromatography(CHCl₃/MeOH 95:5) yielded 2.08 g (6 mmol, 28%) of (E)-diethylβ-(3-methoxyphenyl)-α-(3-pyridyl)-vinylphosphonate and 0.18 g (0.5 mmol,2.4%) of (Z)-Diethyl β-(3-methoxyphenyl)-α-(3-pyridyl)-vinylphosphonateas yellow oils.

The two stereoisomers were identified according to the followingspectroscopic data: (E)-diethyl β-(3-methoxyphenyl)-α-(3-pyridyl)-vinylphosphonate MS (m/e)=347: M⁺, 346 (100%): M⁺−1,210: M⁺—PO₃Et₂ NMR(CDCl₃): δ=8.57, 8.47, 7.65 and 7.32 (4m, H each): aromatic H, 3-pyridyl7.7: (d, 1H, J=24 Hz): (Ph)(CH)C═C(P)-pyridine 7.11, 6.78, 6.66 and 6.52(4m, 1H each): aromatic H, substituted phenyl 4.18-4.08 (m, 4H): P—O—CH₂—CH₃ 3.55 (s, 6H): Ph-OCH ₃ 1.30 (t, 6H): P—O—CH₂—CH ₃

(Z)-diethyl β-(3-methoxyphenyl)-α-(3-pyridyl)-vinyl phosphonate MS(m/e)=347: M⁺, 346 (100%): M⁺−1,210: M⁺—PO₃Et₂ NMR (CDCl₃): δ 8.68,8.58, 7.87 and 7.30 (4m, H each): aromatic H, 3-pyridyl 7.32: (d, 1H,J=45 Hz): (Ph)(CH)C═C(P)-pyridine 7.11, 6.78, 6.66 and 6.52 (4m, 1Heach): aromatic H, substituted phenyl 3.98-3.80 (m, 4H): P—O—CH ₂—CH₃3.87 (s, 6H): Ph-OCH ₃ 1.06 (t, 6H): P—O—CH ₂—CH ₃

Example 9 Diethyl β-(3-methoxyphenyl)-α-(3-pyridyl)-ethylphosphonate

A solution of a mixture of (E)-and (Z)-diethylβ-(3-methoxyphenyl)-α-(3-pyridyl)-vinylphosphonate (1 g, 2.88 mmol) in50 ml ethanol was hydrogenated over 0.5 g of 10% Pd/C catalyst in a Parrhydrogenation apparatus at an initial pressure of 50 psi. When hydrogenuptake has ceased, the catalyst was filtered off, the solvent wasevaporated to give 0.78 g (2.23 mmol, 77%) of the title compound as ayellow oil.

MS (m/e)=349: M⁺, 211 (100%): M⁺—HBPO₃Et₂ NMR (CDCl₃): δ=8.44, 8.37,7.72 and 7.22 (4m, 1H each): aromatic H, 3-pyridyl 7.07, 6.65, 6.57 and6.51 (4m, 1H each): aromatic H, substituted phenyl 4.15-3.79 (3m, 4Htotal): P—O—CH ₂—CH₃ 3.68 (s, 3H): Ph-OCH ₃ 3.52-3.46 (m, H):Ph-CH₂—CH(P)-pyridine 3.36-3.28 and 3.17-3.07 (2m, 1H each): Ph-CH₂—CH(P)-pyridine 1.31 and 1.14 (2t, J=7 Hz, 3H each): P—O—CH₂—CH ₃

Example 10 (Z)-Diethyl β-(3,4,5-trimethoxyphenyl)-α-(3-picolyl)-vinylPhosphonate

Diethyl 2-(3-pyridyl)ethylphosphonate was prepared according to thefollowing procedure: 60% NaH (21.2 g, 53 mmol) was suspended in 250 mlTHF. This suspension was cooled to 0° and tetraethylmethylenediphosphonate (72.63 ml, 28 mmol) was added dropwise. 30Minutes after the end of the addition, pyridine-3-carboxaldehyde (28.53g, 27 mmol) in 60 ml THF was added dropwise and the ice bath wasremoved. The mixture was stirred at room temperature for 4 h then H₂O(100 ml) was added dropwise followed by a saturated NH₄Cl solution (100ml). The aqueous phase was separated and extracted with CHCl₃ (3portions of 300 ml). The combined organic layers were dried with MgSO₄and evaporated to give 44 g of a brown oil. Purification of this crudeproduct by column chromatography (CH₂Cl₂/MeOH 9/1) yielded 38.5 g (17mmol, 59%) of diethyl 2-(3-pyridyl)vinylphosphonate. A 50 ml ethanolsolution of this compound (38 g, 16 mmol) was hydrogenated over 11 g of10% Pd/C to give 36 g (148 mmol, 92%) of diethyl3-pyridylethylphosphonate.

In the following step, the whole procedure was carried out at −78° C.and under a nitrogen atmosphere. N,N,N′,N′-tetramethylethylenediamine(7.4 ml, 49 mmol) was added dropwise to a solution of nBuLi 1.6 M (30.9ml, 49 mmol) in 100 ml THF. After 30 min. a solution of diethyl2-(3-pyridyl)ethylphosphonate (4 g, 16.5 mmol) in 7 ml THF was addeddropwise. After 30 min of stirring trimethyl chlorosilane (4.2 ml, 33mmol) was added dropwise, the reaction mixture was stirred for a further30 min then a solution of 3,4,5-trimethoxybenzaldehyde (3.2 g, 17 mmol)in 15 ml THF was added dropwise. The reaction mixture was stirred at−78° for 2 h, then the cooling bath was removed and saturated NH₄Clsolution (70 ml) was added in one portion. The mixture was allowed towarm to room temperature and the aqueous phase was separated andextracted with ether. The combined organic layers were dried with MgSO₄and evaporated to give 8 g of a brown oil. Purification of this crudeproduct by flash chromatography (AcOEt/MeOH 9/1) yielded 2.01 g (4.8mmol, 29%) of (Z)-diethylβ-(3,4,5-trimethoxyphenyl)-α-(3-picolyl)-vinylphosphonate as a yellowoil.

MS (m/e)=421 (100%): M⁺, 284: M⁺—PO₃Et₂ NMR (CDCl₃): δ=8.57, 8.50, 7.66and 7.28 (4m, H each): aromatic H, 3-pyridyl 7.40: (d, J=47 Hz, 1H):(Ph)(CH)C═C(P)—CH₂-pyridine 6.87 (s, 2H): aromatic H, substituted phenyl3.92-3.76 (m, 4H): P—O—CH ₂—CH₃ 3.87 (s, 6H) and 3.85 (s, 3H): Ph-OCH ₃3.78 (d, J=14 Hz, 2H): (Ph)(CH)C═C(P)—CH ₂-pyridine 1.07 (t, 6H):P—O—CH₂—CH ₂

Example 11 (E)-Diethylβ-(3,4,5-trimethoxyphenyl)-α-(3-picolyl)-vinylphosphonate

Tetraethyl 2-(3-pyridyl)ethylene-1,1-diphosphonate was preparedaccording to the following procedure: Under a nitrogen atmosphere,titanium tetrachloride (41 ml, 369 mmol) was added dropwise to a 600 mlof THF solution cooled to 0° C. by means of an ice bath, followed bypyridine-3-carboxaldehyde (18 g, 168 mmol). Tetraethylmethylenediphosphonate (53.3 g, 183 mmol) dissolved in 60 ml THF wasadded dropwise, followed by N-methylmorpholine (75 g, 741 mmol) and theresulting mixture was stirred at room temperature overnight. Thereaction mixture was then partitioned between water and chloroform, theorganic phase was washed until neutral pH, dried over MgSO4 andevaporated. The residue was purified by column chromatography(CHCl₃/MeOH 95/5) to give 11.5 g (30 mmol, 18%) of tetraethyl2-(3-pyridyl)ethenylidene-1,1-diphosphonate a brown oil. A 100 mlethanol solution of this compound (11.5 g, 30 mmol) was hydrogenatedover 2 g of 10% Pd/C to give 2.73 g (7.2 mmol, 24%) of tetraethyl2-(3-pyridyl)ethylidene-1,1-diphosphonate.

In the following step, the whole procedure was carried out at −78° C.and under a nitrogen atmosphere. Diisopropylamine (2.8 ml, 20 mmol) wasadded dropwise to a solution of nBuLi 1.6 M (12.4 ml, 20 mmol) in 100 mlTHF. After 30 min. a solution of tetraethyl2-(3-pyridyl)ethylidenediphosphonate (2.5 g, 6.6 mmol) in 7 ml TBF wasadded dropwise. After 30 min of stirring a solution of3,4,5-trimethoxybenzaldehyde (1.3 g, 6.6 mmol) in 9 ml THF was addeddropwise. The reaction mixture was stirred at −78° for 2 h, then thecooling bath was removed and saturated NH₄Cl solution (50 ml) was addedin one portion. The mixture was allowed to warm to room temperature andthe aqueous phase was separated and extracted with ether. The combinedorganic layers were dried with MgSO₄ and evaporated to give 3.5 g of abrown oil. Purification of this crude product by flash chromatography(AcOEt/MeOH 9/1) yielded 0.68 g (1.6 mmol, 24%) of (E)-diethylβ-(3,4,5-trimethoxyphenyl)-α-(3-picolyl)-vinylphosphonate as a yellowoil. The (Z)-isomer was isolated as a secondary product (0.35 g, 12%).

MS (m/e)=421 (100%): M⁺, 283: M⁺—HPO₃Et₂ NMR (CDCl₃): δ=8.53, 8.46, 7.58and 7.22 (4m, H each): aromatic H, 3-pyridyl 7.71: (d, J=24 Hz, 1H):(Ph)(CH)C═C(P)CH₂-pyridine 6.55 (s, 2H): aromatic H, substituted phenyl4.12-3.96 (m, 4H): P—O—CH ₂—CH₃ 3.93 (d, J=19.5 Hz, 2H):(Ph)(CH)C═C(P)—CH ₂-pyridine 3.84 (s, 3H) and 3.67 (s, 6H): Ph-OCH ₃1.22 (t, 6H): P—O—CH₂—CH ₃

Example 12 Diethylβ-(3,4,5-trimethoxyphenyl)-α-(3-picolyl)-ethylphosphonate

A solution of a mixture of (E)-and (Z)-diethylβ-(3,4,5-trimethoxyphenyl)-α-(3-picolyl)-vinylphosphonate (0.8 g, 1.9mmol) in 50 ml ethanol was hydrogenated over 0.3 g of 10% Pd/C catalystin a Parr hydrogenation apparatus at an initial pressure of 50 psi. Whenhydrogen uptake has ceased, the catalyst was filtered off, the solventwas evaporated to give 0.6 g of a dark oil. This crude product waspurified by column chromatography (AcOEt/MeOH 9/1) to yield 0.41 g (0.97mmol, 51%) of the title compound as a yellow oil.

MS (m/e)=423: M⁺, 285 (100%): M⁺—HPO₃Et₂ NMR (CDCl₃): δ=8.41, 8.38, 7.37and 7.13 (4m, 1H each): aromatic H, 3-pyridyl 6.32 (s, 2H): aromatic H,substituted phenyl 4.08-3.90 (3m, 4H total): P—O—CH ₂—CH₃ 3.81 (s, 9H):Ph-OCH ₃ 3.22-3.14, 3.06-2.96, 2.81-2.71 and 2.64-2.55 (4m, 1H each):Ph-CH ₂—CH(P)—CH ₂-pyridine 2.45-2.34 (m, 1H): Ph-CH₂—CH(P)—CH₂-pyridine1.25 and 1.20 (2t, J=7 Hz, 3H each): P—O—CH₂—CH ₃

Example 13 Summary of Synthesized Compounds

Summarized in TABLE 1 are a number ofα-substituted-heteroarylalkylphosphonates of formula (I) where X⁵ is Hand n=0. TABLE 1 Cpd X¹ X² X³ X⁴ m Formula Het R¹, R² 1 H OMe H H 0(Ia^(Z)) 3-pyridyl Et 2 H OMe H H 0 (Ia^(E)) 3-pyridyl Et 3 H OMe H H 0(Ib) 3-pyridyl Et 4 H OMe OMe OMe 0 (Ia^(E)) 3-pyridyl Et 5 H OMe OMeOMe 0 (Ia^(Z)) 3-pyridyl Et 6 H OMe OMe OMe 1 (Ia^(Z)) 3-pyridyl Et 7 HOMe OMe OMe 1 (Ia^(E)) 3-pyridyl Et 8 H OMe OMe OMe 1 (Ib) 3-pyridyl Et9 OMe H OMe OMe 0 (Ia^(E)) 3-pyridyl Et 10 OMe H OMe OMe 0 (Ib)3-pyridyl Et 11 OMe H OMe OMe 1 (Ia^(Z)) 3-pyridyl Et 12 OMe H OMe OMe 1(Ib) 3-pyridyl Et 13 H OEt OH H 0 (Ia^(E)) 3-pyridyl Et 14 H OEt OH H 0(Ib) 3-pyridyl Et 15 Me Me OH Me 0 (Ia^(E)) 3-pyridyl Et 16 Me Me OH Me0 (Ia^(E)) 3-pyridyl Et 17 H OMe OH OMe 0 (Ia^(E)) 3-pyridyl Et 18 H OMeOH OMe 0 (Ib) 3-pyridyl Et 19 H OMe OH OMe 0 (Ia^(E)) 5-(2-methyl Etpyridyl) 20 H OMe OH OMe 0 (Ib) 5-(2-methyl Et pyridyl) 21 H OMe OH OMe0 (Ib) 5-(2-methyl iPr pyridyl) 22 H OMe OH Me 0 (Ia^(E)) 3-pyridyl Et23 H OMe OH Me 0 (Ib) 3-pyridyl Et 24 H OMe OH Me 0 (Ia^(E)) 5-(2-methylEt pyridyl) 25 H OMe OH Me 0 (Ib) 5-(2-methyl Et pyridyl) 26 H OMe OH Me0 (Ib) 5-(2-methyl iPr pyridyl) 27 H OMe OH OMe 0 (Ia^(E)) 4-(2-methylEt thiazolyl) 28 H OMe OH Me 0 (Ia^(E)) 4-(2-methyl Et thiazolyl) 29 HOMe OH Me 0 pyrazinyl Et 30 H OMe OH Me 0 (Ib) pyrazinyl Et

Example 14 Biological Data

A. Lp(a) Lowering Activity

1. In Vitro Data

The compounds of formula (1) were assayed for being able to effectivelylower the production of apo (a) in primary cultures of Cynomolgushepatocytes.

Protocol—Hepatocytes were isolated from livers of male adult Cynomolgusmonkeys by the two-step collagenase perfusion method according to C.Guguen-Guillouzo and A. Guillouzo “Methods for preparation of adult andfetal hepatocytes” p. 1-12 in “Isolated and Cultured Hepatocytes”, leseditions Inserm Paris and John Libbey Eurotext London (1986).

The viability of cells was determined by Trypan blue staining. The cellswere then seeded at a density of 1.5-2.10⁵ viable cells per 2 cm² in 24well tissue culture plates in a volume of 500 μl per well of Williams Etissue culture medium containing 10% fetal calf serum. Cells wereincubated for 6-24 hours at 37° C. in a CO₂ incubator (5% CO₂) in thepresence of 20 μM of the test compounds dissolved in ethanol. Four wellswere used for each compound. Nicotinic acid and steroid hormones wereused as references to validate the assay system since they are known todecrease apo (a) in man. Control cells were incubated in the presence ofethanol only.

The amount of apo (a) secreted in culture medium was assayed directly byELISA using a commercially available kit. Changes in apo (a)concentration in culture medium are given as the percentage of valuemeasured for the control plates.

Results—The compounds No. 4, 5, 6, 7, 9, 10, 13, 14, 15, 16. 17, 18, 19,20, 22, 23, 24 and 25 tested at 20 μM were found to lower the apo (a)secretion in the range between −15% to −40%.

2. In Vivo Data

Study Protocol—Male cynomolgus monkeys weighing between 3 and 7 kg weredivided into groups of 3 to 4 animals each. Prior to treatment theirplasma Lp(a) levels were followed over a two-month period to ascertain aconstant baseline value. Test compounds were given orally by gavage atthe dose of 50 mg/kg/day for 2 weeks and Lp(a) was measured at days 7and 14. At the end of the dosing period, animals were maintained for atreatment free period of 4 weeks, whereupon the decreased plasma Lp(a)levels returned to pretreatment levels. This control provided proof thatthe decrease in Lp(a) measured was caused by the pharmacologicalactivity of the test compounds. At Days −1 and 7 or 14, after anovernight fast blood samples were collected on EDTA and Lp(a) wasmeasured by the highly sensitive and specific ELISA test. Results (meanof 34 values of each group) were expressed as % of pre-dose (Day −1).

Results—Selected compounds of formula (1) were tested under theexperimental conditions to investigate their pharmacological activity invivo. The compounds No 23 and 25 lower plasma Lp(a) in the range of −20%to −29% (values measured at Day 7 or 14, % changes from pre-dose at Day−1).

B. Cholesterol Lowering Activity

Study Protocol. Male cynomolgus monkeys weighing between 3 and 7 kg aredivided into groups of 3 to 4 animals each. Prior to treatment, theirplasma cholesterol, LDL cholesterol and apo B levels are followed over aone-month period to ascertain a constant baseline value. Test compoundsare given orally by gavage at the dose of 50 mg/kg/day for 2 weeks andapo B, LDL cholesterol, and total plasma cholesterol are measured atdays 7 and 14. At the end of the dosing period, animals are maintainedfor a treatment-free period of 4 weeks, whereupon their cholesterollevels returned to pre-treatment levels. This control provides proofthat the decrease in cholesterol measured is caused by thepharmacological activity of the test compounds. At Days −1 and 7 or 14,after an overnight fast, blood samples are collected on EDTA and apo Bis measured by an ELISA method (Morwell diagnostics), LDL cholesterol byan immuno turbidimetric method (Boehringer) and total plasma cholesterolby an enzymatic method (CHOD-PAP, Boehringer). Results (mean of 3-4values of each group) are expressed as % of pre-dose (Day −1).

1. A compound of formula (Ia):

or a compound of formula (Ib):

in which: X¹, X², X³, X⁴ and X⁵ are independently hydrogen, hydroxy,hydroxymethyl, C₁-C₃ alkoxymethyl, straight or branched C₁-C₈ alkyl,straight or branched C₁-C₈ alkoxy, C₃-C₆ cycloalkyl, C₃-C₆ cycloalkoxy,cyano, nitro or halogen, wherein said halogen is fluoro, chloro, bromoor iodo; or X² may be combined with X³, or X⁴ may be combined with X⁵,to form a 5- to 6-membered alkylidenedioxy ring optionally substitutedwith a C₁-C₄ alkyl group; or X⁴ may be combined with X⁵ to form a 5- to6-membered alkylidene ring optionally substituted with a C₁-C₄ alkylgroup; R¹ and R² are independently hydrogen or a straight or branchedC₁-C₆ alkyl; B is CH₂, CH₂—CH₂ or CH═CH; n is zero or 1; m is zero, 1 or2; Het is an optionally substituted heteroaryl group comprising at leastone nitrogen atom, or a pharmaceutically acceptable salt thereof.
 2. Thecompound of claim 1, wherein said compound is a compound of formula(Ia).
 3. The compound of claim 1, wherein said compound is a compound offormula (Ib).
 4. The compound of claim 3, wherein said compound offormula (Ib) is the Z-isomer, the E-isomer, or a mixture thereof.
 5. Thecompound of claim 1, wherein X¹ is hydrogen, or methyl, X² is methoxy,ethoxy, methyl, tert-butyl or hydroxy, X³ is hydrogen, hydroxy, methoxy,methyl, ethyl or hydroxymethyl, X⁴ is hydrogen, methoxy, tert-butyl ormethyl and X⁵ is hydrogen.
 6. The compound of claim 5, wherein X² ismethoxy, X³ is hydroxy and X⁴ is methyl or methoxy.
 7. The compound ofclaim 5, wherein m is zero or
 1. 8. The compound of claim 5, wherein nis zero.
 9. The compound of claim 5, wherein R¹ and R² are independentlyC₁-C₃ alkyl.
 10. The compound of claim 9, wherein R¹ and R² areindependently ethyl or isopropyl.
 11. The compound of claim 8, wherein mis zero or
 1. 12. The compound of claim 1, wherein Het is optionallysubstituted and comprises a hetroaryl group selected from the groupconsisting of pyridyl, pyrimidyl, pyrazinyl, pyridazinyl, thiazolyl,thiadiazolyl, benzothiazolyl, pyrazolyl and triazinyl.
 13. The compoundof claim 12, wherein said heteroaryl group selected from the groupconsisting of pyridyl, pyrimidyl, pyrazinyl, pyridazinyl, thiazolyl,benzothiazolyl, pyrazolyl and triazinyl is substituted with one or twomethyl groups or one or two methoxy groups or wherein said heteroarylgroup is thiadiazolyl and is substituted by a methyl or a methoxy group.14. The compound of claim 12, wherein Het is pyrazinyl, 3-pyridyl,5-(2-methylpyridyl), 5-(2-methylthiazolyl) pyridyl)
 15. The compound ofclaim 1, wherein said compound is selected from the group consisting of:(E)-diethyl β-(3-ethoxy-4-hydroxyphenyl)-α-(3-pyridyl)vinylphosphonate;diethyl β-(3-ethoxy-4-hydroxyphenyl)-α-(3-pyridyl)ethylphosphonate;(E)-diethylβ-(4-hydroxy-2,3,5-trimethylphenyl)-α-(3-pyridyl)vinylphosphonate;diethylβ-(4-hydroxy-2,3,5-trimethylphenyl)-α-(3-pyridyl)ethylphosphonate;(E)-diethylβ-(3,5-dimethoxy-4-hydroxyphenyl)-α-(3-pyridyl)vinylphosphonate; diethylβ-(3,5-dimethoxy-4-hydroxyphenyl)-α-(3-pyridyl)ethylphosphonate;(E)-diethylβ-(3,5-dimethoxy-4-hydroxyphenyl)-α-(5-(2-methylpyridyl))vinylphosphonate;diethylβ-(3,5-dimethoxy-4-hydroxyphenyl)-α-(5-(2-methylpyridyl))ethylphosphonate;diisopropylβ-(3,5-dimethoxy-4-hydroxyphenyl)-α-(5-(2-methylpyridyl))ethylphosphonate;(E)-diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(3-pyridyl)vinylphosphonate;diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(3-pyridyl)ethylphosphonate;(E)-diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(5-(2-methylpyridyl))vinylphosphonate; diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(5-(2-methylpyridyl))ethylphosphonate; diisopropylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(5-(2-methylpyridyl))ethylphosphonate; (E)-diethylβ-(3,5-dimethoxy-4-hydroxyphenyl)-α-(4-(2-methylthiazolyl))vinylphosphonate;(E)-diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(4-(2-methylthiazolyl))vinylphosphonate; (E)-diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(pyrazinyl)vinylphosphonate;and diethylβ-(4-hydroxy-3-methoxy-5-methylphenyl)-α-(pyrazinyl)ethylphosphonate.16. A pharmaceutical composition comprising a compound of claimed inclaim 1 and a pharmaceutically acceptable carrier.
 17. A method fordecreasing plasma levels of apo (a), lipoprotein(a), apo B, LDLcholesterol and total cholesterol, comprising administration to apatient in need of such treatment of an effective amount of a compoundof claim
 1. 18. A method for the treatment and/or prevention ofthrombosis, comprising administration to a patient in need of suchtreatment an effective amount of a compound of claim
 1. 19. A method forthe treatment and/or prevention of restenosis following angioplasty,comprising administration of an amount effective to decrease plasmalevels of apo (a) and lipoprotein(a) of a compound of claim
 1. 20. Amethod for the treatment and/or prevention of atherosclerosis,comprising administration to a patient in need of such treatment aneffective amount of a compound claim
 1. 21. The method of claim 20,further comprising administering an effective amount of a cholesterolsynthesis inhibitor.
 22. The method of claim 21, wherein saidcholesterol synthesis inhibitor is a statin selected from the groupconsisting of atorvastatin, simvastatin, pravastatin, cerivastatin,fluvastatin, lovastatin and ZD 4522.